Wait until libgbinder 1.1.28 arrives (many thanks to @slava for updating binder-call utility) to SFOS.
Then run on SFOS device:
$ binder-call -o -a -d /dev/puddlejumper window 14 '{ 0 0 0 0 -145 }'
(play with last argument -145 number for adjusting proper value for your device, for position-reset use 0).
Tested on aliendalvik with android 10 support. Seems like setOverscan (transaction #14 used in binder-call above) was removed in android-11 so we’ll need to find another solution if/when aliendalvik moves to android11.